Improvement of survival after surgical resection of pancreatic cancer independent of adjuvant chemotherapy in the past two decades - A meta-regression

Introduction: Surgical resection improves survival in pancreatic ductal adenocarcinoma (PDAC) and adjuvant chemotherapy adds an additional survival-benefit. While surgical technique has improved in recent years, it remains unclear whether these improvements translate into a survival benefit independent of adjuvant chemotherapy. Thus, we aimed to clarify whether survival of patients who were treated with either Gemcitabine (GEM) or who were observed only in randomized controlled trials on adjuvant chemotherapy of PDAC improved over time. Methods: A systematic search of MEDLINE/PubMed was performed to identify randomized controlled trials on adjuvant chemotherapy of PDAC. The search was limited to studies with arms on GEM monotherapy or postoperative observation and studies were grouped by the median year of enrolment and the use of GEM. Subsequently, a meta-regression on the effect of the median year of enrolment on patient survival was performed. Results: A total of 13 studies with 2469 patients was included, with median years of enrollment ranging from 1996 to 2015. While disease-free survival decreased in patients with postoperative observation (18.0 vs. 5.0 months, p = 0.001), median survival improved over time in patients with postoperative observation (15.8 vs. 18.4 months, p = 0.01) and in patients treated with adjuvant GEM (22.8 vs. 35.0 months, p < 0.001). One- (p <= 0.01) and two-year survival (p = 0.056) improved in both patients treated with adjuvant GEM and those observed only. Conclusion: Survival after surgical resection of PDAC has improved since 1996, even in patients who did not receive adjuvant chemotherapy. Improved surgical technique and postoperative management are likely to be causative factors. (C) 2020 Elsevier Ltd, BASO - The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.